Functional Surfactant-Induced Long-Range Compressive Strain in Curved Ultrathin Nanodendrites Boosts Electrocatalysis.

Curved ultrathin PtPd nanodendrites (CNDs) with long-range compressive strain and highly branched feature are first prepared by a functional surfactant-induced strategy. Precise synthesis realized the construction of both curved and flat PtPd nanodendrites (NDs) with the same atomic ratio, which contributed to exploration of the strain effect on electrocatalytic performance alone. Abundant evidence is provided to confirm that the long-range compressive strain in curved PtPd architectures can effectively tailor the local coordination environment of active sites, lower the position of the d-band center, weaken the adsorption energy of the intermediates (e.g., H* and CO*), and ultimately increase their intrinsic activity. The density functional theory (DFT) calculations further reveal that the introduction of compressive strain weakens the Gibbs free-energy of the intermediate (ΔGH*), which is favorable for accelerating the hydrogen evolution reaction (HER) kinetics. A similar enhanced electrocatalytic performance can also be found in the methanol oxidation reaction (MOR).

Self-assembly of intramolecularly hydrogen-bonded amphiphilic diboronic acid for saccharide recognition.

HYPOTHESIS: The designed organic boronic acid molecule featuring both hydrophilic and hydrophobic moieties, makes a potential functional surfactant. Selective recognition of saccharides through morphological changes of phenylboronic acid-based self-assembly system by saccharide stimulation is a key concept in boronic acid design. EXPERIMENTS: In the present study, we designed a tuning-fork-shaped amphiphilic diboronic acid (OPAB-C8) which formed vesicular aggregates through self-assembly in aqueous solution and evaluated its saccharide recognition function. The formation of the vesicular aggregates was determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The response of OPAB-C8 to saccharide was measured through ultraviolet-visible (UV-vis) titration experiments. FINDINGS: The stoichiometric ratio of OPAB-C8 and glucose complex was 1:2, while that of fructose or galactose was 1:1, and OPAB-C8 showed excellent binding affinity to glucose with binding constant was up to 4.6 × 106 M-2. When dealing with glucose, the vesicular aggregates transformed to larger aggregates, whereas the vesicular aggregates disassembled in the presence of fructose. The results revealed that the selective recognition of saccharides through morphological changes was feasible by diboronic acid self-assembled in aqueous solution.